Der Einflu� der Erdatmosph�re bei astronomischen Beobachtungen

Siedentopf, Heinrich

doi:10.1007/bf00626633

Cited by 15 publications

(3 citation statements)

References 15 publications

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“…where b is a parameter that depends mostly on the height of the observatory (h obs ), and α is a power law index that depends on the size of the aerosol grains. Although an α ∼1.3, derived by Siedentopf (1948), is widely used, we adopted a value of α =0.8 for consistency with the previous study of the extinction curve at Calar Alto (Hopp & Fernandez 2002). The Ozone extinction is a selective absorption by molecular bands.…”

Section: Contributions To the Extinctionmentioning

confidence: 99%

The Night Sky at the Calar Alto Observatory

Sánchez¹,

Aceituno²,

Thiele³

et al. 2007

PUBL ASTRON SOC PAC

106

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We present a characterization of the main properties of the night-sky at the Calar Alto observatory for the time period between 2004 and 2007. We use optical spectrophotometric data, photometric calibrated images taken in moonless observing periods, together with the observing conditions regularly monitored at the observatory, such as atmospheric extinction and seeing. We derive, for the first time, the typical moonless night-sky optical spectrum for the observatory. The spectrum shows a strong contamination by different pollution lines, in particular from Mercury lines, which contribution to the sky-brightness in the different bands is of the order of ∼0.09 mag, ∼0.16 mag and ∼0.10 mag in B, V and R respectively. Regarding the strength of the Sodium pollution line in comparison with the airglow emission, the observatory does not fulfill the IAU recomendations of a dark site. The zenith-corrected values of the moonless night-sky surface brightness are 22. 39, 22.86, 22.01, 21.36 and 19.25 mag arcsec −2 in U , B, V , R and I, which indicates that Calar Alto is a particularly dark site for optical observations up to the I-band. The fraction of astronomical useful nights at the observatory is ∼70%, with a ∼30% of photometric nights. The typical extinction at the observatory is κ V ∼0.15 mag in the Winter season, with little dispersion. In summer the extinction has a wider range of values, although it does not reach the extreme peaks observed at other sites. The analysis of the Winter and summer extinction curves indicates that the Rayleigh scattering is almost constant along the year. The rise of the extinction in the summer season is due to an enhance of the Aerosol extinction, most probably associated with an increase of dust in the atmosphere. The median seeing for the last two years (2005-6) was ∼0.90 ′′ , being smaller in the Summer (∼0.87 ′′ ) than in the Winter (∼0.96 ′′ ). We conclude in general that after 26 years of operations Calar Alto is still a good astronomical site. Its main properties are similar in many aspects to those of other major observatories where 10m-like telescopes are under operation or construction, being a natural candidate for future large aperture optical telescopes.

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Section: Contributions To the Extinctionmentioning

confidence: 99%

The Night Sky at the Calar Alto Observatory

Sánchez¹,

Aceituno²,

Thiele³

et al. 2007

PUBL ASTRON SOC PAC

106

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“…With Elwert's radiation values 3 obtained for a temperature of 10 6 °K and with the values of the absorption cross section given by Schneider 22 and Siedentopf, 23 we have calculated the absorption for different ranges of wavelength as a function of the height (Fig. 4.)…”

Section: Ionization By X-raysmentioning

confidence: 99%

Origin of the IonosphericELayer

Rawer¹,

Argence²

1954

Phys. Rev.

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The intensity of solar soft x-rays (50-• -230A) as computed by Elwert is found to be sufficient to cause the ionization of the ionospheric E layer. On the other hand, preionization of molecular oxygen by ultraviolet chromospheric radiation (X<1020A, Nicolet) could perhaps also be admitted, if it could be accepted that the dissociation of atmospheric oxygen occur in a high transition layer of considerable thickness (100-150 km). The first process is probably predominant.

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“…What occurs during the day cannot be stated from these considerations. SIEDENTOPF (1948) recently published a new theory of formation of the D-layer and postulates an X-ray radiation of 1-2 A originating from the Sun's corona as the causitive agent. The very hot corona can deliver enough electron energy to produce X-rays.…”

Section: -70mentioning

confidence: 99%

The Lowest of the Ionized Layers of the Upper Atmosphere

Stranz¹

1950

Tellus

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The “Stockwerk‐Gliederung” of the Earth's atmosphere introduced by Penndorf and Flohn is a promising method to describe the different atmospheric regions from the nearest to the ground up to the highest levels. The region above the upper inversion (at ca. 75 km) up to 100 km height is generally called the D‐layer which means the lowest of the ionized regions in the upper atmosphere of the Earth. The behaviour of the D‐layer, its most reasonable theory of formation, and its function with regard to the propagation of electromagnetic waves are discussed. Features related to solar‐terrestrial phenomena are shown. Theories and ideas by various authors are compared with each other. The complete investigation from which this paper gives an extract is being published elsewhere.

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Der Einflu� der Erdatmosph�re bei astronomischen Beobachtungen

Cited by 15 publications

References 15 publications

The Night Sky at the Calar Alto Observatory

The Night Sky at the Calar Alto Observatory

Origin of the IonosphericELayer

The Lowest of the Ionized Layers of the Upper Atmosphere

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